Photographing apparatus and focus detection method using the same

A photographing apparatus for automatically detecting a focus via a phase difference detection scheme, the photographing apparatus including an image sensor comprising a plurality of phase difference pixels and configured to acquire an image of a subject; an addition processor configured to add output signals of the plurality of phase difference pixels; a controller configured to detect the focus of the image based on output signals of the plurality of phase difference pixels, and to set an addition range of the plurality of phase difference pixels added by the addition processor based on information of the detected focus and information of the acquired image of the subject.